AbstractExploring the naturally occurring genetic variation of the wild barley genepool has become a major target of barley crop breeding programmes aiming to increase crop productivity and sustainability in global climate change scenarios. However this diversity remains unexploited and effective approaches are required to investigate the benefits that unadapted genomes could bring to crop improved resilience. In the present study, a set of Recombinant Chromosome Substitution Lines (RCSLs) derived from a cross between an elite barley cultivar ‘Harrington’ used as the recurrent parent, and Hordeum vulgare subsp. spontaneum accession (Caesarea 26-24) from the Fertile Crescent, as the donor parent, have been utilised in field and controlled conditions to examine the contribution of wild barley genome as a source of novel allelic variation for the cultivated barley genepool.
Field evaluations in rain-out shelter over two growing seasons and contrasting water regimes revealed wide genetic variability among the RCSLs for relevant morphological, developmental and agronomic traits. Despite the generalised diminished performance of the RCSLs as compared to the elite parent, these were found to significantly improve grain weight and favour broader stability of this trait. The high-throughput genotypic characterisation of the lines with over 1,800 SNP polymorphic SNPs (Infinium iSelect 9K SNP chip), allowed QTLs associated with phenotypic variation to be identified using a mixed model approach. The study revealed novel QTLs for which candidate genes with putative effects on the mobilisation and accumulation of photo-assimilates during grain filling, could potentially lead to genetic gains in yield by optimising the crop sink strength. Also, QTLs associated with traits conferring adaptation to drought-prone environments such as plant cuticular waxes were identified. In addition, a two-dimensional paper growth pouch experiment revealed genotypic variation for root traits such as seminal root elongation rate, root diameter and gravitropism that could potentially determine differences in soil water and nutrient acquisition from early stages of development in restrictive environments.
This study has highlighted the role of exotic germplasm to contribute novel allelic variation by using an optimised experimental approach focused on an exotic genetic library. The results obtained constitute a step forward to the development of more tolerant and resilient varieties. Further investigation in groups of near isogenic lines need to be conducted to confirm the results of this experiments and narrow down the genetic basis of traits conferring adaptability to the crop.
|Date of Award||2016|
|Supervisor||Joanne Russell (Supervisor), Timothy S. George (Supervisor) & Robbie Waugh (Supervisor)|